help! parasitic drain from the fuse labeled "ECU B" - Toyota Yaris Forums

rob_salsa · 02-22-2012, 03:06 PM

I have narrowed the drain to the fuse labeled "ECU B" via a multi meter. does anybody know which part(s) connect to that fuse? its a 7.5 fuse if that helps.

thanks for the help

CTScott · 02-22-2012, 03:09 PM

That is normal. There is about a 100-150 mA draw on that circuit with the car off. It powers the ECM, keyless entry ECU (if so equipped), radio memory backup, etc. The ECM alone draws over 80 mA when it is sleeping.

rob_salsa · 02-22-2012, 03:19 PM

if thats normal then what is wrong? i havnt made any changes to the car in 6 months since i installed a bluetooth kit. this past 4 days the battery has been dead about 6 times. once i jump it it starts and runs fine, if i shut if off and come back in an hour, its fine. but after 3 hours or more i come back and it wont start, the battery is dead again.

going along the idea of parasitic drain as the problem, i was pulling about 0.180 Amps with the car shut off, after removing the EBU B fuse it went down to 0.004 Amps draw.

if you have any advice or suggestions i woul db glad to hear it. thanks.

CTScott · 02-22-2012, 04:52 PM

180 mA is a little bit high. How did the bluetooth kit connect power-wise? Did it connect to the radio's power connector and did it have both a constant and an ignition switched power wire?

It may also just be that your battery is reaching the end of its useful life, where that parasitic drain is enough overnight to bring it below where it can crank the starter.

180 mA over a 12 hour period equals 2.16 Ah of discharge. The OEM battery is a 45 Ah battery, of which you can safely draw it down to 22.5 Ah, without damaging the cells. At your rate of parasitic drain, that would take 5 days to reach.

rob_salsa · 02-23-2012, 01:28 PM

it did connect to the radio's power, i dont know if it had the ignition wire, but it would turn on with the ignition so i would guess so.

i took the battery to the parts store and they did a test on it. after a new battery; the problems seems to have gone away. thanks for the help

02-22-2012, 03:06 PM	#1
rob_salsa Drives: stock 07 toyota yaris s sedan Join Date: Feb 2012 Location: ca Posts: 3	help! parasitic drain from the fuse labeled "ECU B" I have narrowed the drain to the fuse labeled "ECU B" via a multi meter. does anybody know which part(s) connect to that fuse? its a 7.5 fuse if that helps. thanks for the help

02-22-2012, 03:09 PM	#2
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	That is normal. There is about a 100-150 mA draw on that circuit with the car off. It powers the ECM, keyless entry ECU (if so equipped), radio memory backup, etc. The ECM alone draws over 80 mA when it is sleeping. __________________

02-22-2012, 04:52 PM	#4
CTScott ULTIMATE View User's Garage Drives: 09 5dr LB, 2x 08 3dr LB Join Date: Oct 2008 Location: USA, CT Posts: 13,460	180 mA is a little bit high. How did the bluetooth kit connect power-wise? Did it connect to the radio's power connector and did it have both a constant and an ignition switched power wire? It may also just be that your battery is reaching the end of its useful life, where that parasitic drain is enough overnight to bring it below where it can crank the starter. 180 mA over a 12 hour period equals 2.16 Ah of discharge. The OEM battery is a 45 Ah battery, of which you can safely draw it down to 22.5 Ah, without damaging the cells. At your rate of parasitic drain, that would take 5 days to reach. __________________

02-22-2012, 03:19 PM	#3
rob_salsa Drives: stock 07 toyota yaris s sedan Join Date: Feb 2012 Location: ca Posts: 3	if thats normal then what is wrong? i havnt made any changes to the car in 6 months since i installed a bluetooth kit. this past 4 days the battery has been dead about 6 times. once i jump it it starts and runs fine, if i shut if off and come back in an hour, its fine. but after 3 hours or more i come back and it wont start, the battery is dead again. going along the idea of parasitic drain as the problem, i was pulling about 0.180 Amps with the car shut off, after removing the EBU B fuse it went down to 0.004 Amps draw. if you have any advice or suggestions i woul db glad to hear it. thanks.

02-23-2012, 01:28 PM	#5
rob_salsa Drives: stock 07 toyota yaris s sedan Join Date: Feb 2012 Location: ca Posts: 3	it did connect to the radio's power, i dont know if it had the ignition wire, but it would turn on with the ignition so i would guess so. i took the battery to the parts store and they did a test on it. after a new battery; the problems seems to have gone away. thanks for the help